[sdiy] PAiA Tube Head

[John Speth]

> I just took delivery of a PAiA Tube Head kit.  
> 
> First - any good mods?

Yes.  Aside from the obvious fixes that you'd give any
PAIA kit (engineering the cheapness out), you'll
quickly find the power supply to couple in way too
much ripple on the output to be useful at even the
moderate gain settings (signal lost in the hum).

The problem is there's no regulated PS voltage
supplying the wide-range variable gain amps that are
built up around the panel gain pots.  There's a sinful
amount of 60 Hz noise on the PS voltage.

I suggest you build it up as directed, observe the
noise problem, build an off-board regulator circuit,
and then hook it in permanantly afer some A/B tests. 
That's what I did, at least.  My regulator circuit
used a 7815 plus the right zener and a few well chosen
caps and resistors.  The result is a much quieter
circuit and I can cascade both channels for some real
deep distortion when I want.

#2 mod is bring all the jacks to the from panel so you
front panel patching capability.  Doing so gives you
the opportunity to use switched jacks to normalize the
patching.  I chose IN2 to connect to OUT1 when nothing
is plugged into IN2 (or something like that).

Good luck.

JJS






 
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